Mitch, I remember something similar about 8/10 years ago or so.
I can’t recall which vehicle/manufacturer it was, but it was on WPMS and the situation was caused by the price of the vehicle in question either requiring a small AP and fixed weekly payments or a nil AP and Total Allowance. It was on a knife edge as to which should apply,
I think the manufacturer wanted it one way, but Motability wanted it the other way.
It was sorted out in a few weeks and I believe Motability won out.
Dave